Fiber bragg grating sensor testing equipment and testing method

Abstract

The invention provides a fiber grating sensor testing device and method, and the device comprises a temperature box which is configured to adjust the temperature and maintain the temperature at a preset temperature; the stretching mechanism partially stretches into the temperature box, the tested piece is located in the temperature box and installed on the stretching mechanism, the stretching mechanism is constructed to move to a preset position so as to stretch the tested piece, and the tested piece is a fiber grating sensor; the fiber bragg grating demodulation device is configured to demodulate the reflection wavelength of the measured piece to obtain wavelength data; and the acquisition and processing device is configured to acquire displacement data of the measured piece and obtain a strain sensitivity coefficient based on the wavelength data, or acquire temperature data of the measured piece and obtain a temperature sensitivity coefficient based on the wavelength data.

Description

Technical Field

[0001] At least one embodiment of the present invention relates to the field of optical fiber sensing technology, and in particular to an optical fiber Bragg grating sensor testing device and a testing method. Background Art

[0002] Fiber Bragg grating sensor is a sensor that uses the grating structure in the optical fiber to sense the change of external physical quantity. It is a kind of optical fiber sensor, which has the characteristics of high sensitivity, anti-electromagnetic interference, corrosion resistance, small size and ability to work in harsh environment.

[0003] The basic principle of fiber Bragg grating sensor is to use the periodic change structure of refractive index (i.e. grating) in optical fiber to reflect light of specific wavelength. When fiber Bragg grating is affected by external factors (such as temperature, stress, pressure, etc.), its periodic structure of refractive index will change, resulting in a change in the wavelength of reflected light. By detecting the change in the wavelength of reflected light, the change in external physical quantity can be known. The elastic-optic effect caused by strain will cause the reflected wavelength of fiber Bragg grating to change. At the same time, the thermo-optic effect and thermal expansion caused by temperature will also cause the reflected wavelength of fiber Bragg grating to change. Therefore, when calibrating the parameters of fiber Bragg grating strain temperature sensor in the laboratory, the temperature sensitivity coefficient and strain sensitivity coefficient need to be tested and calculated. Summary of the invention

[0004] In view of this, the present invention provides a fiber grating sensor testing device and a testing method, which are used to at least partially solve the above technical problems. By generating a temperature change field and a strain change field, both the temperature sensitivity coefficient and the strain sensitivity coefficient can be obtained, thereby improving the convenience and efficiency of the test.

[0005] According to a first aspect of the present invention, there is provided a fiber grating sensor testing device, comprising an incubator configured to adjust the temperature and maintain the temperature at a preset temperature; a stretching mechanism partially extending into the incubator, wherein a test piece is located in the incubator and mounted on the stretching mechanism, and the stretching mechanism is configured to move to a preset position to stretch the test piece, wherein the test piece is a fiber grating sensor; a fiber grating demodulation device configured to demodulate the reflection wavelength of the test piece to obtain wavelength data; and an acquisition and processing device configured to acquire displacement data of the test piece and obtain a strain sensitivity coefficient based on the wavelength data, or to acquire temperature data of the test piece and obtain a temperature sensitivity coefficient based on the wavelength data.

[0006] According to an embodiment of the present invention, the acquisition and processing device includes: an image acquisition device configured to acquire a speckle image of the test piece; and a processing module, reconstructing the three-dimensional spatial coordinates of the test piece based on the speckle image to obtain displacement data of the test piece.

[0007] According to an embodiment of the present invention, the acquisition and processing device further includes a platinum resistance temperature meter installed at a position adjacent to the measured object to acquire temperature data of the measured object.

[0008] According to an embodiment of the present invention, the stretching mechanism includes: a platform, a first end of the platform is located in the incubator, and a second end is located outside the incubator; a first loading platform is arranged at the first end of the platform; a second loading platform is arranged opposite to the first loading platform and is slidably mounted on the platform; a driving assembly is arranged at the second end of the platform and partially extends into the incubator, and is constructed to drive the second loading platform to move in a direction close to or away from the first loading platform, so as to stretch the test piece installed between the first loading platform and the second loading platform.

[0009] According to an embodiment of the present invention, a plurality of mounting holes are provided on the first stage and the second stage, and the plurality of mounting holes are distributed in an array to mount the test piece.

[0010] According to an embodiment of the present invention, the driving component includes: a linear grating ruler installed on the platform; a reading head installed on the second stage and configured to read real-time position data on the linear grating ruler in real time as the second stage moves; a stepper motor arranged at the first end of the platform; a motor driver configured to adjust and control the stepper motor based on the real-time position data fed back by the reading head; and a driving rod threadedly connected to the second stage and constructed to rotate under the drive of the stepper motor to drive the second stage to move to the preset position.

[0011] According to an embodiment of the present invention, it also includes: a bearing, which is arranged at a position of the temperature box that allows the drive rod to extend into the first adapter port in the temperature box and cooperates with the drive rod; a sealing ring, which is located on the side of the bearing to seal the first adapter port.

[0012] According to an embodiment of the present invention, the stretching mechanism further includes a guide rail mounted on the platform and parallel to the driving rod to guide the second stage to slide.

[0013] According to the second aspect of the present invention, there is also provided a testing method for a fiber grating sensor testing device, comprising installing a piece to be tested on a stretching mechanism, adjusting the stretching mechanism so that the piece to be tested is in a tensioned state; adjusting the temperature of an incubator to a plurality of preset temperatures, collecting temperature data and wavelength data of the piece to be tested corresponding to the plurality of preset temperatures, and obtaining a temperature sensitivity coefficient; or, when the preset temperature is constant, based on the strain measurement range of the piece to be tested, selecting a plurality of preset positions at which the stretching mechanism stretches the piece to be tested, and collecting position data and wavelength data of the piece to be tested corresponding to the plurality of preset positions, and obtaining a strain sensitivity coefficient.

[0014] According to an embodiment of the present invention, the preset temperature range is -30°C to +80°C, and the strain range of the measured object is ±5000με.

[0015] According to the fiber grating sensor testing device and testing method provided by the present invention, the test piece is installed on the stretching mechanism and is located in the incubator. The temperature of the incubator is adjusted to multiple preset temperatures to generate a temperature change field. At each preset temperature, the temperature data of the test piece is collected by the acquisition and processing device, and the wavelength data is obtained by the fiber grating demodulation device. Based on the multiple temperature data and the corresponding wavelength data, the temperature sensitivity coefficient is obtained. When the temperature of the incubator is maintained at the preset temperature, the stretching mechanism moves to multiple preset positions to stretch the test piece to generate a strain change field. At the same time, the acquisition and processing device collects multiple displacement data of the test piece, and the fiber grating demodulation device obtains wavelength data corresponding to the displacement data. Based on the multiple displacement data and the corresponding wavelength data, the strain sensitivity coefficient is obtained. By setting the acquisition and processing device, the accuracy of data acquisition is improved, and the precision of the test is improved. By generating the temperature change field and the strain change field, both the temperature sensitivity coefficient and the strain sensitivity coefficient can be obtained, thereby improving the convenience and efficiency of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 The working principle diagram of the fiber grating sensor testing device according to the embodiment of the present invention is schematically shown.

[0018] Figure 2 The control principle diagram of the fiber Bragg grating sensor testing device according to the embodiment of the present invention is schematically shown.

[0019] Figure 3 A three-dimensional schematic diagram of a stretching mechanism according to an embodiment of the present invention is schematically shown.

[0020] Figure 4 The flowchart schematically shows a method for testing a fiber Bragg grating sensor testing device according to an embodiment of the present invention.

[0021] Reference numerals

[0022] 1. Temperature box; 11. First adapter port; 12. Second adapter port; 2. Stretching mechanism; 21. Platform; 22. First loading platform; 23. Second loading platform; 24. Driving assembly; 241. Stepping motor; 242. Driving rod; 243. Motor driver; 25. Mounting hole; 3. Fiber grating demodulation device; 4. Collection and processing device; 41. Image collection device; 42. Platinum resistance temperature meter; 5. Bearing; 6. Guide rail; 7. Measured object; 8. Industrial computer; 9. Fiber optic flange. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0024] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0025] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0026] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0027] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present invention. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present invention.

[0028] Fiber Bragg grating sensor is a sensor that uses the grating structure in the optical fiber to sense the change of external physical quantity. It has the characteristics of high sensitivity, anti-electromagnetic interference, corrosion resistance, small size and ability to work in harsh environments. Fiber Bragg grating sensor is a wavelength modulation sensor, which overcomes the weakness of intensity modulation sensor that is easily disturbed by line loss and light source output power fluctuation. When the fiber Bragg grating is affected by external factors (such as temperature, stress, pressure, etc.), the periodic structure of its refractive index will change, resulting in a change in the wavelength of the reflected light. By detecting the change in the wavelength of the reflected light, the change of the external physical quantity can be known.

[0029] The elasto-optic effect caused by strain (tensile strain or compressive strain) will cause the reflected wavelength of the fiber Bragg grating to change. At the same time, the thermo-optic effect and thermal expansion caused by temperature will also cause the reflected wavelength of the fiber Bragg grating to change. Therefore, when calibrating the parameters of the fiber Bragg grating strain temperature sensor in the laboratory, it is necessary to test and calculate the temperature sensitivity coefficient and the strain sensitivity coefficient. However, when the fiber Bragg grating sensor is currently tested for temperature, it is usually placed in a constant temperature water bath or a blast drying oven, and it is impossible to apply quantitative stress to the fiber Bragg grating sensor to cause an equal amount of strain; or when the fiber Bragg grating sensor is tested for strain, it is impossible to quantitatively change the temperature of the fiber Bragg grating sensor.

[0030] Figure 1 The working principle diagram of the fiber grating sensor testing device according to the embodiment of the present invention is schematically shown.

[0031] The embodiment of the present invention provides a fiber grating sensor testing device, such as Figure 1 As shown, the fiber Bragg grating sensor testing equipment includes an incubator 1, a stretching mechanism 2, a fiber Bragg grating demodulation device 3 and an acquisition and processing device 4. The incubator 1 is configured to adjust the temperature and maintain it at a preset temperature. The stretching mechanism 2 partially extends into the incubator 1. The test piece 7 is located in the incubator 1 and is installed on the stretching mechanism 2. The stretching mechanism 2 is configured to move to a preset position to stretch the test piece 7. Among them, the test piece 7 is a fiber Bragg grating sensor. The fiber Bragg grating demodulation device 3 is configured to demodulate the reflection wavelength of the test piece 7 to obtain wavelength data. The acquisition and processing device 4 is configured to collect displacement data of the test piece 7 and obtain a strain sensitivity coefficient based on the wavelength data, or collect temperature data of the test piece 7 and obtain a temperature sensitivity coefficient based on the wavelength data.

[0032] It should be noted that the measured object 7 is a fiber grating sensor. When the temperature or the expansion and contraction strain changes, the periodic structure of the refractive index of the measured object 7 will change, thereby causing the wavelength of the reflected light to change. By detecting the change in the wavelength of the reflected light, the change in temperature or expansion and contraction strain can be known.

[0033] The temperature box 1 can adjust the temperature to the desired preset temperature and generate a constant temperature field. The stretching mechanism 2 partially extends into the temperature box 1, and the test piece 7 is located in the temperature box 1 and installed on the stretching mechanism 2, thereby reducing the influence of temperature changes on the accuracy of the stretching mechanism 2 controlling the stretching of the test piece 7 and the displacement data measurement accuracy of the test piece 7. By setting the temperature box 1 and the stretching mechanism 2 to cooperate, the control of precise strain and temperature changes can be achieved.

[0034] According to an embodiment of the present invention, the test piece 7 is mounted on the stretching mechanism 2 and is located in the incubator 1. The temperature of the incubator 1 is adjusted to a plurality of preset temperatures to generate a temperature change field. At each preset temperature, the temperature data of the test piece 7 is collected by the acquisition and processing device 4, and the wavelength data is obtained by the fiber Bragg grating demodulation device 3. Based on the plurality of temperature data and the corresponding wavelength data, the temperature sensitivity coefficient is obtained. When the temperature of the incubator 1 is maintained at a preset temperature, the stretching mechanism 2 moves to a plurality of preset positions to stretch the test piece 7 to generate a strain change field. At the same time, the acquisition and processing device 4 collects a plurality of displacement data of the test piece 7, and the fiber Bragg grating demodulation device 3 obtains the wavelength data corresponding to the displacement data. Based on the plurality of displacement data and the corresponding wavelength data, the strain sensitivity coefficient is obtained. By setting the acquisition and processing device 4, the accuracy of data acquisition is improved, and the precision of the test is improved. By generating the temperature change field and the strain change field, both the temperature sensitivity coefficient and the strain sensitivity coefficient can be obtained, thereby improving the convenience and efficiency of the test.

[0035] Figure 2 The control principle diagram of the fiber Bragg grating sensor testing device according to the embodiment of the present invention is schematically shown.

[0036] In an exemplary embodiment, Figure 1 and Figure 2 As shown, the fiber grating sensor test equipment also includes an industrial computer 8 to achieve overall control. Specifically, the industrial computer 8 is used to control the stretching mechanism 2 to move to a preset position and control the temperature box 1 to adjust to a preset temperature. The industrial computer 8 processes the acquisition and processing device 4, thereby completing the automated test of the temperature sensitivity coefficient and strain sensitivity coefficient of the test piece 7.

[0037] In an exemplary embodiment, Figure 1 and Figure 2As shown, the acquisition and processing device 4 includes an image acquisition device 41 and a processing module. The image acquisition device 41 is configured to acquire a speckle image of the test piece 7. The processing module reconstructs the three-dimensional space coordinates of the test piece 7 based on the speckle image to obtain the displacement data of the test piece 7. Specifically, the image acquisition device 41 can be a camera or a camera, etc., and is configured to acquire a speckle image or a marker point image of the test piece 7.

[0038] Specifically, the working band of the image acquisition device is the visible light band of 400-800nm, the focal length range of the field of view is greater than 15mm, the resolution is not less than 1920×1080, and the frame rate is not less than 25Hz.

[0039] In such an embodiment, when the temperature is constant and the test piece 7 is at the initial position, the image acquisition device 41 acquires the speckle image of the test piece 7 to form a two-dimensional image. It is understandable that in order to improve the quality of the speckle image, an additional light source can be added for fill light as needed. The processing module reconstructs the initial displacement data of the three-dimensional spatial coordinates of the test piece 7 through image processing technology based on the speckle image. When the stretching mechanism 2 moves to a plurality of preset positions and stretches the test piece 7, the displacement data of the test piece 7 corresponding to the plurality of preset positions are obtained. Since there is a difference between the moving displacement of the stretching mechanism 2 and the displacement change of the test piece 7 after stretching, the displacement data of the test piece 7 after the stretching strain can be accurately measured by the acquisition and processing device 4. The acquisition and processing device 4 is located outside the temperature box 1 to realize non-contact measurement, and avoids the measurement device being located in the temperature box 1 and being affected by temperature changes and affecting the measurement accuracy, thereby improving the measurement accuracy of the displacement data.

[0040] It should be noted that, based on the strain measurement range requirement of the measured object 7, the maximum displacement of the stretching mechanism 2 is obtained, and multiple preset positions are selected within the maximum displacement range. The stretching mechanism 2 is at multiple preset positions, and the acquisition and processing device 4 collects multiple displacement data of the measured object 7, and obtains the strain sensitivity coefficient based on the multiple displacement data and the corresponding wavelength data to achieve precise strain control and measurement.

[0041] Figure 3 The schematic diagram of the three-dimensional drawing mechanism 2 according to the embodiment of the present invention is shown.

[0042] In an exemplary embodiment, Figure 1 and Figure 3 As shown, the acquisition and processing device 4 also includes a platinum resistance temperature meter 42 installed at a position adjacent to the measured object 7 to collect temperature data of the measured object 7.

[0043] It should be noted that due to the large spatial range within the temperature chamber 1, there is a slight difference between the temperature near the test piece 7 and the temperature of the chamber wall or other locations of the temperature chamber 1. The platinum resistance temperature meter 42 is located near the test piece 7, which is close to the actual temperature of the test piece 7 itself, further improving the accuracy of the temperature data measurement.

[0044] According to an embodiment of the present invention, when the strain force is constant, the temperature of the incubator 1 is adjusted to the initial preset temperature, and the preset time is maintained so that the temperature in the incubator 1 is constant, and the platinum resistance temperature meter 42 measures the initial temperature data of the test piece 7. Among them, the preset time can be 8 minutes, 9 minutes, 10 minutes, 11 minutes, and 12 minutes, which is determined according to actual needs. The temperature of the incubator 1 is changed to multiple preset temperatures, and the preset time is maintained so that the temperature in the incubator 1 is constant, and the platinum resistance temperature meter 42 measures multiple temperature data of the test piece 7.

[0045] In an exemplary embodiment, Figure 1 and Figure 3 As shown, the stretching mechanism 2 includes a platform 21, a first loading platform 22, a second loading platform 23 and a driving assembly 24. The first end of the platform 21 is located inside the incubator 1, and the second end is located outside the incubator 1. The first loading platform 22 is disposed at the first end ( Figure 3 The second loading platform 23 is arranged opposite to the first loading platform 22 and is slidably mounted on the platform 21. The driving assembly 24 is arranged at the second end ( Figure 3 The right end of the second stage 23 extends partially into the temperature box 1 and is configured to drive the second stage 23 to move toward or away from the first stage 22 so as to stretch the test piece 7 installed between the first stage 22 and the second stage 23.

[0046] In an exemplary embodiment, Figure 1 and Figure 3 As shown, the tension range of the stretching mechanism 2 is 50N to 100N, the displacement range is not less than ±5mm, and the displacement measurement error is not greater than 0.1μm. The drive component 24 is located outside the incubator 1 and is in a room temperature environment to avoid being affected by the temperature change of the incubator 1, thereby improving the accuracy and reliability of the test. The test piece 7 is mounted on the first stage 22 and the second stage 23 and is located in the incubator 1 to control the second stage 23 to move to a preset position under the drive of the drive component 24. The incubator 1 can provide a temperature change field and maintain a constant preset temperature. By generating a temperature change field and a strain change field, both the temperature sensitivity coefficient and the strain sensitivity coefficient can be obtained, thereby improving the convenience and efficiency of the test.

[0047] In an exemplary embodiment, Figure 3As shown, the platform 21 is a plate-like structure, the middle part of the platform 21 passes through the side wall of the temperature box 1, and is sealed with the temperature box 1 through a sealing ring. The first end of the platform 21 is provided with a plurality of assembly holes for mounting the first stage 22, so as to adjust the position of the first stage 22, thereby adjusting the minimum distance between the first stage 22 and the second stage 23, so as to adapt to the test pieces 7 of different lengths.

[0048] In an exemplary embodiment, Figure 3 As shown, a plurality of mounting holes 25 are provided on the first stage 22 and the second stage 23, and the plurality of mounting holes 25 are arranged in an array, so that the test piece 7 can be mounted between the first stage 22 and the second stage 23 by means of a pressing plate and bolts. In this way, the position of the mounting hole 25 can be adjusted according to the length of the test piece 7, and it is suitable for different types of test pieces 7.

[0049] In an exemplary embodiment, Figure 3 As shown, the drive assembly 24 includes a linear grating ruler, a reading head, a stepper motor 241, a motor driver 243 and a driving rod 242. The linear grating ruler (not shown in the figure) is mounted on the platform 21 and extends in the length direction of the platform 21. The reading head (not shown in the figure) is mounted on the second stage 23 and is configured to read the real-time position data on the linear grating ruler in real time as the second stage 23 moves. The stepper motor 241 is arranged at the first end of the platform 21. The motor driver 243 is configured to adjust and control the stepper motor 241 based on the real-time position data fed back by the reading head. The driving rod 242 is threadedly connected to the second stage 23 and is constructed to rotate under the drive of the stepper motor 241 to drive the second stage 23 to move to a preset position.

[0050] According to an embodiment of the present invention, driven by the stepper motor 241 and the driving rod 242, the second stage 23 moves in a direction away from the first stage 22. The reading head mounted on the second stage 23 moves with the movement of the second stage 23, and reads the real-time position data on the linear grating ruler in real time. The motor driver 243 adjusts and controls the stepper motor 241 based on the real-time position data fed back, thereby effectively eliminating the error caused by the transmission gap of the stepper motor 241, so that the driving component 24 accurately controls the second stage 23 to move to a preset position.

[0051] In an exemplary embodiment, Figure 3 As shown, the fiber grating sensor test equipment also includes a bearing 5 and a sealing ring. The bearing 5 is arranged at a position of the temperature box 1 that allows the driving rod 242 to extend into the first adapter port 11 in the temperature box 1, and cooperates with the driving rod 242 to guide the movement of the driving rod 242. The sealing ring is located on the side of the bearing 5 and is dynamically sealed with the driving rod 242, thereby sealing the first adapter port 11 and improving the sealing performance of the temperature box 1.

[0052] In an exemplary embodiment, Figure 3 As shown, the stretching mechanism 2 also includes a guide rail 6, which is installed on the platform 21 and is parallel to the driving rod 242 to guide the second stage 23 to slide. In this way, the friction resistance between the second stage 23 and the platform 21 can be reduced, and the stability of the second stage 23 during movement and the positioning accuracy of the second stage 23 can be improved.

[0053] In an exemplary embodiment, Figure 1 and Figure 3 As shown, a second adapter port 12 is provided on the side wall of the temperature box 1, and a fiber flange 9 is provided at the position of the second adapter port 12. The fiber grating demodulation device 3 is located outside the temperature box 1, and is connected to the device under test 7 through an optical fiber cable and the optical fiber flange 9 to demodulate the reflection wavelength of the device under test 7 to obtain wavelength data.

[0054] According to the embodiment of the present invention, when the moving position of the stretching mechanism 2 is constant, the temperature sensitivity coefficient is obtained based on the platinum resistance temperature sensor 42 collecting multiple temperature data of the test piece 7 and the corresponding wavelength data collected by the fiber Bragg grating demodulation device 3. When the temperature of the incubator 1 is constant, the stretching mechanism 2 stretches the test piece 7 to multiple preset positions, and the image acquisition device 41 and the processing module collect multiple displacement data of the test piece 7 and the corresponding wavelength data collected by the fiber Bragg grating demodulation device 3 to obtain the strain sensitivity coefficient.

[0055] The embodiment of the present invention further provides a method for testing a fiber grating sensor testing device, including operations S110 - S120 .

[0056] Figure 4 The flowchart schematically shows a method for testing a fiber Bragg grating sensor testing device according to an embodiment of the present invention.

[0057] In operation S110, the test piece 7 is mounted on the stretching mechanism 2, and the stretching mechanism 2 is adjusted so that the test piece 7 is in a tensioned state.

[0058] In operation S120, the temperature of the incubator 1 is adjusted to a plurality of preset temperatures, and the temperature data and wavelength data of the test piece 7 corresponding to the plurality of preset temperatures are collected to obtain a temperature sensitivity coefficient; or, when the preset temperature is constant, based on the strain measurement range of the test piece 7, a plurality of preset positions at which the stretching mechanism 2 stretches the test piece 7 are selected, and the position data and wavelength data of the test piece 7 corresponding to the plurality of preset positions are collected to obtain a strain sensitivity coefficient.

[0059] In an exemplary embodiment, the preset temperature range is -30°C to +80°C, and the strain range of the test piece 7 is ±5000με.

[0060] Specifically, in operation S110, the temperature box 1, the fiber Bragg grating demodulation device 3 and the acquisition and processing device 4 are initialized and configured. The stretching mechanism 2 is adjusted so that the test piece 7 is in a tensioned state. The image acquisition device 41 of the acquisition and processing device 4 is adjusted so that the test piece 7 is in the center of the line of sight of the image acquisition device 41. The surface of the test piece 7 is processed to ensure that the image acquisition device 41 can acquire the speckle image of the test piece 7, so as to reconstruct the three-dimensional space coordinates of the test piece 7 based on the speckle image and obtain the displacement data of the test piece 7.

[0061] In operation S120, when testing the temperature sensitivity coefficient, the stretching mechanism 2 is in a constant position, the temperature of the incubator 1 is adjusted to the initial temperature, and the temperature is maintained constant for a preset time. The preset time can be 8 minutes, 9 minutes, 10 minutes, 11 minutes, or 12 minutes, which is determined according to actual needs. The temperature of the incubator 1 is adjusted to a preset temperature, and the preset temperature range is -30°C to +80°C. The temperature data of the test piece 7 detected by the platinum resistance temperature meter 42 in the acquisition and processing device 4 is The fiber Bragg grating demodulation device 3 is used to obtain the wavelength data corresponding to the measured object in different temperature data. . Repeat the measurement for each preset temperature several times. The temperature sensitivity coefficient of the DUT is calculated using the least square method based on the temperature data and wavelength data.

[0062] When testing the strain sensitivity coefficient, adjust the temperature of the incubator to the preset temperature. , and maintain the temperature constant for a preset time. When the stretching mechanism stretches the test piece to a taut state, the initial position of the stretching mechanism is According to the strain measurement range requirements of the measured object, the maximum displacement change of the stretching mechanism is obtained Among them, the strain range of the measured piece is ±5000με. to A plurality of preset positions are selected within the range. At each preset position, the image acquisition device of the acquisition and processing device acquires the speckle image of the measured object. The processing module of the acquisition and processing device reconstructs the three-dimensional space coordinates of the measured object based on the speckle image to obtain the displacement data of the measured object. At each preset position, the wavelength data corresponding to the measured object 7 is obtained by the fiber grating demodulation device 3 The strain sensitivity coefficient of the measured object is calculated based on the displacement data and wavelength data using the least square method.

[0063] Among them, the expression of strain sensitivity coefficient is:

[0064] (1);

[0065] in, is the strain sensitivity coefficient; is the wavelength change; is the dependent variable.

[0066] but The expression to be calculated is as follows:

[0067] (2);

[0068] (3);

[0069] in, is the strain value of the i-th calibration point; is the initial preset position; The i-th preset position; is the strain sensitivity coefficient; The wavelength value outputted by the i-th preset position test point; and are the average strain values ​​and the average wavelength values ​​of all test points at preset positions respectively; n is the number of preset positions.

[0070] According to the fiber Bragg grating sensor testing device and testing method provided by the present invention, the test piece 7 is installed on the stretching mechanism 2 and is located in the incubator 1. The temperature of the incubator 1 is adjusted to multiple preset temperatures to generate a temperature change field. At each preset temperature, the temperature data of the test piece 7 is collected by the acquisition and processing device 4, and the wavelength data is obtained by the fiber Bragg grating demodulation device 3. Based on the multiple temperature data and the corresponding wavelength data, the temperature sensitivity coefficient is obtained; when the temperature of the incubator 1 is maintained at the preset temperature, the stretching mechanism 2 moves to multiple preset positions to stretch the test piece 7 to generate a strain change field, and at the same time, the acquisition and processing device 4 collects multiple displacement data of the test piece 7, and the fiber Bragg grating demodulation device 3 obtains wavelength data corresponding to the displacement data. Based on the multiple displacement data and the corresponding wavelength data, the strain sensitivity coefficient is obtained. By setting the acquisition and processing device 4, the accuracy of data acquisition is improved, and the precision of the test is improved; by generating the temperature change field and the strain change field, both the temperature sensitivity coefficient and the strain sensitivity coefficient can be obtained, thereby improving the convenience and efficiency of the test.

[0071] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination. The scope of the present invention is defined by the attached claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A fiber grating sensor testing device, characterized in that: include: A thermostat (1) is configured to adjust the temperature and maintain it at a preset temperature; A stretching mechanism (2) partially extends into the temperature box (1), a test piece (7) is located in the temperature box (1) and is mounted on the stretching mechanism (2), the stretching mechanism (2) is configured to move to a preset position to stretch the test piece (7), wherein the test piece (7) is a fiber grating sensor; A fiber Bragg grating demodulation device (3) configured to demodulate the reflection wavelength of the measured object (7) to obtain wavelength data; The acquisition and processing device (4) is configured to acquire displacement data of the measured object (7) and obtain a strain sensitivity coefficient based on the wavelength data, or to acquire temperature data of the measured object (7) and obtain a temperature sensitivity coefficient based on the wavelength data.

2. The fiber Bragg grating sensor testing device according to claim 1, characterized in that: The acquisition and processing device (4) comprises: An image acquisition device (41) configured to acquire a speckle image of the measured object (7); A processing module reconstructs the three-dimensional spatial coordinates of the measured object (7) based on the speckle image to obtain displacement data of the measured object (7).

3. The fiber Bragg grating sensor testing device according to claim 1, characterized in that: The acquisition and processing device (4) also includes a platinum resistance temperature measuring device (42), which is installed at a position adjacent to the measured object (7) to collect temperature data of the measured object (7).

4. The fiber Bragg grating sensor testing device according to claim 1, characterized in that: The stretching mechanism (2) comprises: A platform (21), wherein a first end of the platform (21) is located inside the incubator (1), and a second end of the platform (21) is located outside the incubator (1); A first loading platform (22) is disposed at a first end of the platform (21); A second loading platform (23), arranged opposite to the first loading platform (22), and slidably mounted on the platform (21); A driving assembly (24) is arranged at the second end of the platform (21), partially extending into the temperature box (1), and is configured to drive the second stage (23) to move toward or away from the first stage (22) so as to stretch the test piece (7) installed between the first stage (22) and the second stage (23).

5. The fiber Bragg grating sensor testing device according to claim 4, characterized in that: The first loading platform (22) and the second loading platform (23) are provided with a plurality of mounting holes (25), and the plurality of mounting holes (25) are distributed in an array so as to mount the test piece (7).

6. The fiber Bragg grating sensor testing device according to claim 4, characterized in that: The drive assembly (24) comprises: A linear grating ruler, mounted on the platform (21); A reading head is mounted on the second stage (23) and is configured to read real-time position data on the linear grating ruler in real time as the second stage (23) moves; A stepping motor (241) is arranged at a first end of the platform (21); A motor driver (243) configured to adjust and control the stepper motor (241) based on the real-time position data fed back by the reading head; The driving rod (242) is threadedly connected to the second loading platform (23) and is configured to rotate under the drive of the stepping motor (241) to drive the second loading platform (23) to move to the preset position.

7. The fiber Bragg grating sensor testing device according to claim 6, characterized in that: Also includes: A bearing (5) is arranged at a position of the temperature box (1) that allows the driving rod (242) to extend into a first adapter opening in the temperature box (1), and cooperates with the driving rod (242); A sealing ring is located on the side of the bearing (5) to seal the first adapter port.

8. The fiber Bragg grating sensor testing device according to claim 6, characterized in that: The stretching mechanism (2) further comprises a guide rail (6) which is mounted on the platform (21) and is parallel to the driving rod (242) so as to guide the sliding of the second loading platform (23).

9. A method for testing a fiber Bragg grating sensor testing device according to any one of claims 1 to 8, characterized in that: include: The test piece (7) is mounted on the stretching mechanism (2), and the stretching mechanism (2) is adjusted so that the test piece (7) is in a tensioned state; The temperature of the incubator (1) is adjusted to a plurality of preset temperatures, and the temperature data and wavelength data of the test piece (7) corresponding to the plurality of preset temperatures are collected to obtain a temperature sensitivity coefficient; or, Under the condition of a preset constant temperature, based on the strain measurement range of the test piece (7), a plurality of preset positions at which the stretching mechanism (2) stretches the test piece (7) are selected, and position data and wavelength data of the test piece (7) corresponding to the plurality of preset positions are collected to obtain a strain sensitivity coefficient.

10. The testing method according to claim 9, characterized in that: The preset temperature range is -30°C to +80°C, and the strain range of the measured piece (7) is ±5000με.

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